/*
 *  Copyright 2016 The WebRTC Project Authors. All rights reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#ifndef WEBRTC_API_RTCSTATSCOLLECTOR_H_
#define WEBRTC_API_RTCSTATSCOLLECTOR_H_

#include <map>
#include <memory>
#include <vector>

#include "webrtc/api/datachannelinterface.h"
#include "webrtc/api/stats/rtcstats_objects.h"
#include "webrtc/api/stats/rtcstatsreport.h"
#include "webrtc/base/asyncinvoker.h"
#include "webrtc/base/refcount.h"
#include "webrtc/base/scoped_ref_ptr.h"
#include "webrtc/base/sslidentity.h"
#include "webrtc/base/timeutils.h"

namespace cricket {
class Candidate;
}  // namespace cricket

namespace rtc {
class SSLCertificate;
}  // namespace rtc

namespace webrtc {

class PeerConnection;
struct SessionStats;

class RTCStatsCollectorCallback : public virtual rtc::RefCountInterface {
 public:
  virtual ~RTCStatsCollectorCallback() {}

  virtual void OnStatsDelivered(
      const rtc::scoped_refptr<const RTCStatsReport>& report) = 0;
};

// All public methods of the collector are to be called on the signaling thread.
// Stats are gathered on the signaling, worker and network threads
// asynchronously. The callback is invoked on the signaling thread. Resulting
// reports are cached for |cache_lifetime_| ms.
class RTCStatsCollector : public virtual rtc::RefCountInterface {
 public:
  static rtc::scoped_refptr<RTCStatsCollector> Create(
      PeerConnection* pc,
      int64_t cache_lifetime_us = 50 * rtc::kNumMicrosecsPerMillisec);

  // Gets a recent stats report. If there is a report cached that is still fresh
  // it is returned, otherwise new stats are gathered and returned. A report is
  // considered fresh for |cache_lifetime_| ms. const RTCStatsReports are safe
  // to use across multiple threads and may be destructed on any thread.
  void GetStatsReport(rtc::scoped_refptr<RTCStatsCollectorCallback> callback);
  // Clears the cache's reference to the most recent stats report. Subsequently
  // calling |GetStatsReport| guarantees fresh stats.
  void ClearCachedStatsReport();

 protected:
  RTCStatsCollector(PeerConnection* pc, int64_t cache_lifetime_us);

  // Stats gathering on a particular thread. Calls |AddPartialResults| before
  // returning. Virtual for the sake of testing.
  virtual void ProducePartialResultsOnSignalingThread(int64_t timestamp_us);
  virtual void ProducePartialResultsOnWorkerThread(int64_t timestamp_us);
  virtual void ProducePartialResultsOnNetworkThread(int64_t timestamp_us);

  // Can be called on any thread.
  void AddPartialResults(
      const rtc::scoped_refptr<RTCStatsReport>& partial_report);

 private:
  struct CertificateStatsPair {
    std::unique_ptr<rtc::SSLCertificateStats> local;
    std::unique_ptr<rtc::SSLCertificateStats> remote;
  };

  void AddPartialResults_s(rtc::scoped_refptr<RTCStatsReport> partial_report);
  void DeliverCachedReport();

  // Produces |RTCCertificateStats|.
  void ProduceCertificateStats_s(
      int64_t timestamp_us,
      const std::map<std::string, CertificateStatsPair>& transport_cert_stats,
      RTCStatsReport* report) const;
  // Produces |RTCDataChannelStats|.
  void ProduceDataChannelStats_s(
      int64_t timestamp_us, RTCStatsReport* report) const;
  // Produces |RTCIceCandidatePairStats| and |RTCIceCandidateStats|.
  void ProduceIceCandidateAndPairStats_s(
      int64_t timestamp_us, const SessionStats& session_stats,
      RTCStatsReport* report) const;
  // Produces |RTCPeerConnectionStats|.
  void ProducePeerConnectionStats_s(
      int64_t timestamp_us, RTCStatsReport* report) const;
  // Produces |RTCInboundRTPStreamStats| and |RTCOutboundRTPStreamStats|.
  void ProduceRTPStreamStats_s(
      int64_t timestamp_us, const SessionStats& session_stats,
      RTCStatsReport* report) const;
  // Produces |RTCTransportStats|.
  void ProduceTransportStats_s(
      int64_t timestamp_us, const SessionStats& session_stats,
      const std::map<std::string, CertificateStatsPair>& transport_cert_stats,
      RTCStatsReport* report) const;

  // Helper function to stats-producing functions.
  std::map<std::string, CertificateStatsPair>
  PrepareTransportCertificateStats_s(const SessionStats& session_stats) const;

  PeerConnection* const pc_;
  rtc::Thread* const signaling_thread_;
  rtc::Thread* const worker_thread_;
  rtc::Thread* const network_thread_;
  rtc::AsyncInvoker invoker_;

  int num_pending_partial_reports_;
  int64_t partial_report_timestamp_us_;
  rtc::scoped_refptr<RTCStatsReport> partial_report_;
  std::vector<rtc::scoped_refptr<RTCStatsCollectorCallback>> callbacks_;

  // A timestamp, in microseconds, that is based on a timer that is
  // monotonically increasing. That is, even if the system clock is modified the
  // difference between the timer and this timestamp is how fresh the cached
  // report is.
  int64_t cache_timestamp_us_;
  int64_t cache_lifetime_us_;
  rtc::scoped_refptr<const RTCStatsReport> cached_report_;
};

const char* CandidateTypeToRTCIceCandidateTypeForTesting(
    const std::string& type);
const char* DataStateToRTCDataChannelStateForTesting(
    DataChannelInterface::DataState state);

}  // namespace webrtc

#endif  // WEBRTC_API_RTCSTATSCOLLECTOR_H_
